1. Field of the Invention
This invention generally relates to a solenoid valve or an electrically-powered valve for controlling a flow of fluid such as air. This invention particularly relates to a solenoid valve which can be used in an evaporative control system to selectively block and unblock a charcoal-canister pipe opening into the atmosphere.
2. Description of the Related Art
Japanese patent application publication number 7-233882 (application number 6-24075) discloses a solenoid valve for selectively blocking and unblocking communication between a first passage and a second passage. The solenoid valve in Japanese application 7-233882 includes a fixed iron core, a first movable member, and a second movable member. The fixed iron core is magnetized when a coil is energized. The second movable member is formed of a permanent magnet. The magnetic poles of the permanent magnet are arranged so that the permanent magnet repels the fixed iron core when the coil is energized. As the second movable member moves, the first movable member comes into contact with a valve seat defining a portion of the second passage. When the first movable member is in contact with the valve seat, communication between the first passage and the second passage is blocked. An operation chamber extends between the first movable member and the second movable member. The first movable member includes a valve member and an annular diaphragm. The annular diaphragm extends radially outward from the valve member. Thus, the inner circumferential edge of the diaphragm is connected with the valve member. The outer circumferential edge of the diaphragm is connected with a coil hold member. The valve member is movably supported by the diaphragm. The valve member has a first through hole for providing communication between the operation chamber and the second passage. The diaphragm has a second through hole for providing communication between the operation chamber and the first passage. When the valve member is separated from the valve seat, the operation chamber and the second passage communicate with each other via the first through hole. When the valve member is in contact with the valve seat, the first through hole is closed by the second movable member so that the operation chamber and the second passage are disconnected from each other. On the other hand, the operation chamber and the first passage remain in communication with each other via the second through hole regardless of whether the valve member separates from or contacts with the valve seat.
Japanese patent application publication number 8-312827 (application number 7-115918) discloses a solenoid valve including a coil, a moving core, and a yoke. The coil is supported by a coil hold member. The moving core is moved as the coil is energized and de-energized. The yoke has a valve portion formed with a communication hole and a valve seat around the communication hole. A valve rubber is mounted on the moving core. When the coil is de-energized, the moving core is positioned by a return spring so that the valve rubber is separate from the valve seat. Thus, in this case, the communication hole is unblocked. When the coil is energized, the moving core is moved toward the valve portion of the yoke and the valve rubber comes into contact with the valve seat. Thus, in this case, the communication hole is blocked. The moving core has a cylindrical portion extending into a central bore of the coil hold member.
Japanese patent application publication number 8-270818 (application number 7-69817) discloses a solenoid valve similar in structure to the solenoid valve of Japanese application 8-312827.
It is an object of this invention to provide a solenoid valve which generates only low-level noise or reduced-level noise when a valve member meets a valve seat.
A first aspect of this invention provides a solenoid valve comprising (a) an electromagnetic drive unit for generating a magnetomotive force when being fed with electric power; (b) a member having a controlled-fluid passage and an accommodation chamber containing the electromagnetic drive unit; (c) a partition wall defining a part of the controlled-fluid passage; (d) a valve opening extending through the partition wall; (e) a shaft extending through the valve opening and being driven by the electromagnetic drive unit; (f) a valve member fixed to the shaft and moving into and out of contact with the partition wall to block and unblock the valve opening in accordance with movement of the shaft; (g) a thin-film sealing member made of rubber-based resilient material for airtightly separating the controlled-fluid passage and the accommodation chamber from each other; (h) a communication passage connecting the accommodation chamber and an exterior; and (i) an orifice providing a smaller effective cross-sectional area of the communication passage.
A second aspect of this invention provides a solenoid valve comprising (a) an electromagnetic drive unit for generating a magnetomotive force when being fed with electric power; (b) a member having a controlled-fluid passage and an accommodation chamber containing the electromagnetic drive unit; (c) a partition wall defining a part of the controlled-fluid passage; (d) a valve opening extending through the partition wall; (e) a shaft extending through the valve opening and being driven by the electromagnetic drive unit; (f) a valve member fixed to the shaft and moving into and out of contact with the partition wall to block and unblock the valve opening in accordance with movement of the shaft; and (g) a thin-film sealing member made of rubber-based resilient material for airtightly separating the controlled-fluid passage and the accommodation chamber from each other, the thin-film sealing member having a first portion and a second portion, the second portion extending around the first portion, the first portion being less resiliently deformable than the second portion.
A third aspect of this invention is based on the second aspect thereof, and provides a solenoid valve wherein the first portion is harder than the second portion.
A fourth aspect of this invention is based on the second aspect thereof, and provides a solenoid valve wherein the first portion is thicker than the second portion.
A fifth aspect of this invention is based on the fourth aspect thereof, and provides a solenoid valve wherein the first portion extends over a central area of the thin-film sealing member, and the first portion includes an engagement portion in contact with the shaft and a peripheral portion near the engagement portion.
A sixth aspect of this invention is based on the first aspect thereof, and provides a solenoid valve wherein the partition wall forms a valve seat with which the valve member is moved into and out of contact.
A seventh aspect of this invention is based on the first aspect thereof, and provides a solenoid valve wherein the partition wall has a projection forming a shaft support for locating the shaft radially while allowing axial movement of the shaft.
An eighth aspect of this invention is based on the seventh aspect thereof, and provides a solenoid valve wherein the projection of the partition wall forms a stopper engageable with a projection on the shaft.
A ninth aspect of this invention is based on the seventh aspect thereof, and provides a solenoid valve wherein the projection on the shaft has a cross section of a shape corresponding to an inner shape of the shaft support.
A tenth aspect of this invention provides a solenoid valve comprising a housing defining a fluid passage; a valve seat defining a part of the fluid passage; a valve member movable into and out of contact with the valve seat to block and unblock the fluid passage; a shaft; a fixing member for fixing the valve member to the shaft; a movable iron core holding the shaft and forming a first part of a magnetic circuit; a fixed iron core facing the movable iron core and forming a second part of the magnetic circuit; and a coil extending around the movable iron core and the fixed iron core and generating a magnetic force to move the movable iron core toward the fixed iron core when being fed with electric power; wherein a portion of the fixing member is spaced from a corresponding portion of the valve member by a gap for allowing deformation of the valve member.
An eleventh aspect of this invention is based on the tenth aspect thereof, and provides a solenoid valve wherein the fixing member has a first portion and a second portion, the first portion extending around the second portion and being thinner than the second portion.
A twelfth aspect of this invention is based on the tenth aspect thereof, and provides a solenoid valve wherein the gap is provided by a step on at least one of the fixing member and the valve member.